Many scientists have devoted themselves to the study of the interaction between subwavelength structures and electromagnetic waves. These structures are commonly composed of regular arrays of subwavelength protuberances, which can be artificially designed. However, extending from 2D periodic patterns to 3D disordered subwavelength structures has not been studied yet. In this study, we studied the total diffuse reflectivity of carbon aerogels with various 3D networks of randomly oriented particle-like nanostructures by using normally incident visible light (430-675 nm). We observed that the different 3D network nanostructures of carbon aerogels, especially for the structures with the minimum size, reduced the reflectivity effectively. It was found that the key mechanism for the subwavelength-structure-induced ultralow reflectivity property is due to the decrease of the amplitude of electron vibration forced by the electromagnetic wave, which provides a simple method for designing perfect black materials.

Ca2+-induced Ca2+ release (CICR) enhances a variety of cellular Ca2+ signaling and functions. How CICR affects impulse-evoked transmitter release is unknown. At frog motor nerve terminals, repetitive Ca2+ entries slowly prime and subsequently activate the mechanism of CICR via ryanodine receptors and asynchronous exocytosis of transmitters. Further Ca2+ entry inactivates the CICR mechanism and the absence of Ca2+ entry for >1 min results in its slow depriming. We now report here that the activation of this unique CICR markedly enhances impulse-evoked exocytosis of transmitter. The conditioning nerve stimulation (10–20 Hz, 2–10 min) that primes the CICR mechanism produced the marked enhancement of the amplitude and quantal content of end-plate potentials (EPPs) that decayed double exponentially with time constants of 1.85 and 10 min. The enhancement was blocked by inhibitors of ryanodine receptors and was accompanied by a slight prolongation of the peak times of EPP and the end-plate currents estimated from deconvolution of EPP. The conditioning nerve stimulation also enhanced single impulse- and tetanus-induced rises in intracellular Ca2+ in the terminals with little change in time course. There was no change in the rate of growth of the amplitudes of EPPs in a short train after the conditioning stimulation. On the other hand, the augmentation and potentiation of EPP were enhanced, and then decreased in parallel with changes in intraterminal Ca2+ during repetition of tetani. The results suggest that ryanodine receptors exist close to voltage-gated Ca2+ channels in the presynaptic terminals and amplify the impulse-evoked exocytosis and its plasticity via CICR after Ca2+-dependent priming.

The subject of topological materials has attracted immense attention in condensed-matter physics because they host new quantum states of matter containing Dirac, Majorana, or Weyl fermions. Although Majorana fermions can only exist on the surface of topological superconductors, Dirac and Weyl fermions can be realized in both 2D and 3D materials. The latter are semimetals with Dirac/Weyl cones either not tilted (type I) or tilted (type II). Although both Dirac and Weyl fermions have massless nature with the nontrivial Berry phase, the formation of Weyl fermions in 3D semimetals require either time-reversal or inversion symmetry breaking to lift degeneracy at Dirac points. Here we demonstrate experimentally that canted antiferromagnetic BaMnSb 2 is a 3D Weyl semimetal with a 2D electronic structure. The Shubnikov-de Hass oscillations of the magnetoresistance give nearly zero effective mass with high mobility and the nontrivial Berry phase. The ordered magnetic arrangement (ferromagnetic ordering in the ab plane and antiferromagnetic ordering along the c axis below 286 K) breaks the time-reversal symmetry, thus offering us an ideal platform to study magnetic Weyl fermions in a centrosymmetric material.topological material | nontrivial Berry phase | 3D semimetal T he observation of the quantum Hall effect has led to the discovery of new phases associated with topological ordering. In the past decade, topological materials have emerged as a new frontier of condensed matter physics due to new physical concepts and potential applications. Theory has played a major role in predicting new topological materials, which have been realized experimentally. Topological insulators, which are metallic at the surface but insulating in bulk (for a review, see ref. 1), have been extensively investigated. Surface states in these materials can be described by the Dirac equation with the Fermi surface formed by Dirac points. Dirac fermions are effectively massless because their dispersion is linear in energy. If the bulk is superconducting, the surface hosts Majorana fermions (for a review, see ref.2). More recently, a new class of topological materials, namely, Dirac or Weyl semimetals, has appeared. Such topological semimetals are characterized by the presence of electron and hole pockets touching with either degeneracy (Dirac) or nondegeneracy (Weyl). If both time reversal and inversion symmetries are preserved, the system is a Dirac semimetal (3). If either time-reversal or inversion symmetry is broken, the Dirac points split and turn into Weyl points, making the system a Weyl semimetal (3). If both timereversal and inversion symmetries are broken, the system may become a Weyl superconductor (4).The above framework makes the search of topological semimetals possible. For example, Dirac semimetals should have centrosymmetry to preserve the inversion symmetry. However, a noncentrosymmetric crystal structure would favor Weyl semimetal configuration (5). If a system is centrosymmetric and magnetically ordered, whether time-reversal sy...

Nonsteroidal anti-inflammatory drugs, such as ketoprofen, are generally used to treat pain and inflammation and as pyretic agents in clinical medicine. However, the usage of these drugs may lead to oxidative injury to the gastrointestinal mucosa. Camellia oil ( Camellia oleifera Abel.) is commonly used in Taiwan and China as cooking oil. Traditional remedies containing this oil exert beneficial health effects on the bowel, stomach, liver, and lungs. However, the effects of camellia oil on ketoprofen-induced oxidative gastrointestinal mucosal lesions remain unknown. The objective of this study was to evaluate the effect of camellia oil on ketoprofen-induced acute gastrointestinal ulcers. The results showed that treatment of Int-407 cells with camellia oil (50-75 μg/mL) not only increased the levels of heme oxygenase-1 (HO-1), glutathione peroxidase (GPx), and superoxide dismutase (SOD) mRNA expression but also increased vascular endothelial growth factor (VEGF) and prostaglandin E2 (PGE2) protein secretion, which served as a mucosal barrier against gastrointestinal oxidative injury. Moreover, Sprague-Dawley (SD) rats treated with camellia oil (2 mL/kg/day) prior to the administration of ketoprofen (50 mg/kg/day) successfully inhibited COX-2 protein expression, inhibited the production of interleukin-6 (IL-6) and nitrite oxide (NO), reversed the impairment of the antioxidant system, and decreased oxidative damage in the gastrointestinal mucosa. More importantly, pretreatment of SD rats with camellia oil strongly inhibited gastrointestinal mucosal injury induced by ketoprofen, which was proved by the histopathological staining of gastrointestinal tissues. Our data suggest that camellia oil exerts potent antiulcer effects against oxidative damage in the stomach and intestine induced by ketoprofen.

No abstract

1. The effects of the phosphodiesterase inhibitors caffeine, theophylline, isobutylmethylxanthine (IBMX) and rolipram on spontaneous electrical activity (slow waves) were studied in the circular muscle of the guinea‐pig gastric antrum. 2. All the inhibitors reduced slow wave frequency without changing the membrane potential and the slow wave configuration, but at higher concentrations they blocked the slow waves and caused membrane hyperpolarization. In the presence of the inhibitors a low level of irregular electrical activity could be observed in many preparations. 3. Isoprenaline, forskolin, dibutyryl cAMP and 8‐bromo‐cAMP all produced effects essentially similar to those of phosphodiesterase inhibitors. K+ (12 mM) and removal of K+ both depolarized the membrane and these were not affected by IBMX (1‐3 microM). A decrease in frequency caused by IBMX was also not significantly affected by 12 mM K+ or K+ removal and only partially antagonized by TEA or 4‐aminopyridine. 4. These results suggest that an increase in intracellular cAMP inhibits pacemaker activity of slow waves. An increase in K+ conductance does not seem to be a major factor in this inhibition. Slow waves appear to be a compound electrical activity in a group of muscle cells and are likely to be disintegrated by xanthine derivatives.

On 31 August 2010, more than 100 transient luminous events were observed to occur over Typhoon Lionrock when it passed at ∼210 km to the southwest of the NCKU site in Taiwan. Among them, 14 negative gigantic jets (GJs) with clear recognizable morphologies and radio frequency signals are analyzed. These GJs are all found to have negative discharge polarity and thus are type I GJs. Morphologically, they are grouped into three forms: tree‐like, carrot‐like, and a new intermediate type called tree‐carrot‐like GJs. The ULF and ELF/VLF band signals of these events contain clear signatures associated with GJ development stages, including the initiating lightning, the leading jet, the fully developed jet, and the trailing jet. Though the radio waveform for each group of GJs always contains a fast descending pulse linked with the surge current upon the GJ‐ionosphere contact, the detailed waveforms actually vary substantially. Cross analysis of the optical and radio frequency signals for these GJs indicates that a large surge current moment (CM) (>60 kA‐km) appears to be essentially associated with the tree‐like GJs. In contrast, the carrot‐like and the tree‐carrot‐like GJs are both related to a surge CM less than 36 kA‐km, and a continuing CM less than 27 kA‐km further separates the carrot‐like GJs from the tree‐carrot‐like GJs. Furthermore, on the peak CM versus charge moment change diagram for the initiating lightning, different groups of GJs seem to exhibit different trends. This feature suggests that the eventual forms of negative GJs may have been determined at the initiating lightning stage.

The blue luminous events (BLEs) recorded by ISUAL (Imager of Sprites and Upper Atmospheric Lightning) radiate unambiguous middle ultraviolet to blue emissions (230–450 nm) but contain dim red emissions (623–754 nm). The BLE appears to be dot‐like on one ISUAL image with an integration time of 29 ms. A few BLEs develop upward into blue jets/starters or type II gigantic jets (GJs). The associated sferics of the BLEs in the extremely low frequency to very low frequency band and in the low‐frequency band exhibit similar patterns to the narrow bipolar events (NBEs) identified in the very low frequency and low‐frequency band. The ISUAL BLEs are conjectured to be the accompanied light emissions of the NBEs. Both upward and downward propagating current obtained from the associated sferics of the BLEs have been found. The source heights of the six BLEs related to negative NBEs are estimated in the range of 16.2–17.8 km. These six events are suggested to occur between the upper positive charge layer and the negative screen charge layer on the top of the normally electrified thunderstorm. The six blue starters, one blue jet, and one type II GJ are inferred to be positive upward discharges from their associated sferics in the extremely low frequency to very low frequency band. Based on the simultaneous radio and optical observations, a NBE is conjectured to be the initiation discharge with rapidly flowing current within the thunderstorm, while a blue jet/starter or a type II GJ is suggested to be the ensuing discharge with slowly varying current propagating upward from the thunderstorm.